Plasma characteristics and target erosion profile of racetrack-shaped RF magnetron plasma with weak rubber magnets for full circular target utilization

We have developed the racetrack-shaped RF magnetron plasma with weak rubber magnets (ferrite and neodymium) for the full utilization of the circular target and the reduction of the magnet weight. The magnetic field simulations are analyzed for the ferrite rubber magnets, the neodymium rubber magnets, and the neodymium rubber magnets including the neodymium metal magnets. The magnetic flux density indicates a mountain like profile between the magnets, having a maximum for the neodymium rubber and metal magnets. It is found that the ion flux to the target has a peak in the gap between two rubber magnets and the value remarkably increases with the addition of neodymium metal magnets. The erosion of the circular copper target, with 100 mm in diameter, has been studied by rotating the racetrack-shaped RF magnetron plasma for the neodymium rubber magnets including the neodymium metal magnets. It is seen that radial profile of the erosion depth keeps roughly constant until r = 20 mm and then decreases gradually away from the center for RF power of 40 W, Ar gas pressure of 2 Pa and sputtering time of 4 h. The target utilization is approximately 72% estimated from the erosion profile.